Mobile Usability Testing to Prevent Fat Finger Syndrome

Fat Finger Syndrome is continuously problematic for mobile usability testing. While some might blame the user for being inattentive and clumsy, the fact of the matter is that the user interface is at fault. After all, the purpose of good design is to ensure that factors that might frustrate or confuse users are eliminated

Recently, there were several occasions during mobile usability testing where I came across a layout in which a hamburger placed alongside the logout icon was used to represent the menu. The user will surely become annoyed with being required to log back in.

This annoyance is the result of incorrect target zones and spacing of elements, especially on the smaller screen.

Below are a few recommendations for you to prevent fat fingers from affecting your design:

• Bear in mind that thumbs are the most common input method. Almost half of users (49%) manage their devices with one hand, with 67% of them using their right hand. Of the remaining 33%, 72% of them use their thumb.
• Together with thumbs, fingertips, and finger pads are also used while interacting with a mobile touchscreen. Be sure to take these into consideration when sizing touch zones, designing icons, and incorporating whitespace.
• With large touch targets, there’s less of a possibility for user touch error.
• Average finger and thumb width is 45-57 px and 72 px respectively.
• In deciding the target screen position, remember that thumbs are the main input method. Stretching your thumb to the far side of a screen is far easier than the near side.

It is imperative that you conduct mobile usability tests to avoid fat finger syndrome when developing applications.